Vehicles such as buses are typically provided with air conditioning units for conditioning the air within the interior of the bus. These air conditioning units may include both heating and cooling functions and are generally mounted on the roof of the bus with inlets and outlets provided in communication with the interior of the bus for conditioning the air within the interior of the bus.
A number of roof mounted air conditioner units have been developed which incorporate both the evaporator and condenser functions in a single package and include evaporator coils at the suction side of air flow passage.
For example, U.S. Pat. No. 5,605,055 Roof Mounted Air Conditioner describes units which incorporate both of the evaporator and condenser functions in a single package wherein pairs of condenser and evaporator coils are located outboard of the longitudinal axis. Other examples of such units are shown in U.S. Pat. Nos. 4,926,655 and 5,005,372 among others.
These units suffer some disadvantages, in particular, water which may condense on the surface of the coils under the negative static pressure. This condensation of liquid must be evacuated from the air conditioner unit or else it may leak into the interior of the bus.